Prior to the conception and subsequent development of the present invention, as is generally well recognized in the prior art, flexible type diaphragms are a necessary integral component in a variety of piston type pumps.
To the best of applicant's knowledge, each of these prior art flexible type diaphragms has been secured to one end of a rod-like piston member that is positioned within the pump housing where it is connected for reciprocal movement. A portion of a metallic flange-like member is inserted through an aperture that is disposed in the geometric center of such flexible type diaphragm member and then bolted to such rod-like piston member to secure such flexible type diaphragm into an operating position.
As can best be seen in FIG. 1, which has been labeled prior art in the attached drawings, this flange-like member has a relatively large metal surface area that has always been exposed to the particular material to be pumped. This exposed relatively large metal surface area is known to be a source of undesirable contamination as well as a likely location where detrimental type bacteria can grow.
Consequently, in certain well known and extremely critical type applications which require sanitary type conditions, such as usage in either the food industry or in the medical field, it has been the common practice for stainless type steels to be used in the production of the flange-like member to be used to secure the flexible type diaphragm to such rod-like piston member. Even though these stainless type steels can be produced to rather exacting standards they still exhibit a number of significant problems in their use in these highly critical sanitary type applications.
One such problem, for example, is that it does not completely eliminate sites where such detrimental type bacteria can start to grow because there are still crevices where the flange-like member is attached to the flexible type diaphragm. A second significant problem is associated with cleaning these prior art flexible type diaphragms between uses. In addition, the use of stainless steel to produce these flange-like members is rather expensive in comparison to either cast iron or plastic, for example.
Applicant is aware of, and has been involved in, a number of previous attempts to incorporate an insert type member into the back portion of these flexible type diaphragms in order to have a substantially uniform non-obtrusive surface area which will be in contact with the particular material to be pumped. One such prior attempt, for example, involved the addition of an extra layer of relatively expensive nylon type reinforcement to the flexible type diaphragm.
However, each of these prior attempts was unsuccessful. The primary reason why these prior attempts were unsuccessful was the fact that these insert type members could be pulled out of such flexible type diaphragm with relative ease due to the necessary reciprocal pumping action of the rod-like piston member. When this situation occurs the pump is then left in a broken and unusable condition.